KR101562680B1 - X-ray inspection device and x-ray inspection method - Google Patents

Abstract

Ray absorption edge of an element included in the measurement sample and has an energy characteristic higher than that of the X-ray absorption edge of the detection element An X-ray detector 11 for detecting X-rays transmitted through the specimen, an X-ray detector 13 for detecting the X-rays transmitted through the specimen, and an arithmetic unit for obtaining a contrast image from the transmitted X- 15) and an X-ray transmission method.

Description

X-RAY INSPECTION DEVICE AND X-RAY INSPECTION METHOD [0002]

The present invention relates to an X-ray penetration inspection apparatus and an X-ray penetration inspection method capable of detecting foreign matter composed of specific elements in a sample.

2. Description of the Related Art In recent years, lithium ion secondary batteries having higher energy density than nickel-based batteries have been employed as batteries for automobiles, hybrid cars, electric vehicles and the like. This lithium ion secondary battery is a kind of non-aqueous electrolyte secondary battery, which is a secondary battery in which lithium ions in the electrolyte take charge of electric conduction and does not contain metal lithium in the battery. In a notebook type personal computer or a mobile phone It has already been adopted a lot.

This lithium ion secondary battery has excellent battery characteristics. However, if a foreign substance such as Fe (iron) enters the electrode during the manufacturing process, the reliability of the battery characteristics such as deterioration of battery characteristics such as heat generation and lifetime is affected Therefore, until now, mounting on a vehicle has been delayed. For example, as shown in Fig. 4A, an electrode (positive electrode) of a lithium ion secondary battery is formed by laminating a lithium cobalt oxide film or a Mn oxide film on both surfaces of an Al film 1, (Iron) or SUS (stainless steel) foreign matter X may be mixed into the lithium film 2 as shown in Fig. 4 (b) If the foreign matter X is several tens of 탆 or more, there is a possibility that a short circuit occurs and battery loss or performance deterioration may occur. For this reason, it is demanded that the lithium-ion secondary battery be quickly detected by the inspection of the battery containing the foreign matter X at the time of manufacture and removed in advance.

Generally, a method using a transmitted X-ray is known as a method for detecting foreign matter in a sample. With this technique, there has been proposed a foreign substance detection method of a carbonaceous material which detects the presence or absence of foreign matter incorporation into a carbon-based material or the like used as a cathode of a lithium ion secondary battery by transmission X-ray 1).

Patent Document 1: Japanese Patent Application Laid-Open No. 2004-239776 (Claims)

The above-described conventional techniques have the following problems.

That is, in the conventional foreign matter detection method, the presence or absence of foreign matter is detected merely by the intensity of the transmitted X-ray. Therefore, if the atomic numbers of the foreign matters are largely different, a clear contrast can be obtained. There is a problem that it becomes difficult to discriminate. For example, Co (atomic number 27) contained as one of the constituent elements in the electrode (positive electrode plate) serving as a measurement sample and Fe (atomic number 26) of the element constituting the foreign object to be detected have the same contrast . For this reason, in the conventional foreign matter detection method, as shown in Fig. 4A, in the transmission X-ray image T of the electrode (positive electrode plate) serving as the measurement sample S, There is a problem that the contrast due to the thick portion 2a or the contrast caused by the foreign matter X can not be discriminated as shown in Fig.

It is an object of the present invention to provide an X-ray penetration inspection apparatus and an X-ray penetration inspection method which can clearly detect only the contrast due to foreign matter and prevent over detection and false detection .

In order to solve the above-described problems, the present invention employs the following configuration. That is, in the X-ray penetration inspection apparatus and the X-ray transmission inspection method of the present invention, an element which is lower than the X-ray absorption edge of one element included in the measurement sample and which is to be detected (hereinafter referred to as "detection element" ) Of the X-ray absorption edge of the characteristic X-ray is transmitted to the measurement specimen, the X-ray transmitted when the characteristic X-ray penetrates the measurement specimen is received and detected by the X-ray detector, And a contrast image is obtained by calculating from the transmission image showing the distribution of the intensity of the transmitted X-ray.

The characteristic X-ray to be irradiated on the measurement sample uses a filter formed of an element having an X-ray absorption edge of the energy between the Kα line and the Kβ line of the characteristic X-ray to remove the Kβ line in the characteristic X-ray.

In these X-ray penetration inspection apparatuses and X-ray transmission inspection methods, monochromatic is formed by characteristic X-rays having an energy lower than the X-ray absorption edge of one element contained in the measurement sample and higher than that of the X- To obtain a transmission image, so that a clear contrast image for a specific element can be obtained. That is, by using a high-energy monochromatic X-ray of the X-ray absorption edge of the element rather than an X-ray in which various energies such as white X-rays are mixed, even if another element having a close atomic number is present, It becomes possible to obtain an image.

In addition, since a filter formed of an element having an X-ray absorption edge of the energy between the Kα line and Kβ line of the characteristic X-ray is disposed between the measurement sample and the X-ray tube, the Kβ line of the characteristic X- . Therefore, only the desired characteristic X-rays are extracted and irradiated to the sample, so that the contrast of the element to be measured becomes clearer.

The X-ray penetration inspection apparatus of the present invention is characterized in that the measurement sample contains lithium cobalt oxide, the X-ray conduit is a Ni target port, the detection element is Fe, and the filter is a Co foil.

That is, the X-ray penetration inspection apparatus of the present invention is characterized in that, as a measurement sample, lithium cobalt oxide is a typical containing substance, and when a foreign substance mainly containing Fe is detected in the measurement sample, one constituent of lithium cobalt oxide (7.709 keV) of the element Co, and the characteristic X-ray of energy higher than the X-ray absorption edge of Fe (7.111 keV) of the detection element, 7.477 keV). Thus, Fe can be detected with a clear contrast by using an inexpensive X-ray tube.

In addition, the X-ray permeability test apparatus of the present invention can extract only the Ni-K? Characteristic X-ray (7.477 keV) using a filter of Co (X-ray absorption edge = 7.709 keV) foil and irradiate the measurement sample.

Further, the X-ray penetration inspection apparatus of the present invention is characterized in that the measurement sample contains lithium manganese oxide, the X-ray conduit is an Fe target conduit, the detection element is Cr, and the filter is a Mn foil.

That is, the X-ray penetration inspection apparatus of the present invention is characterized in that, as a measurement sample, lithium manganese oxide is a representative containing substance, and when a foreign matter mainly containing Cr is detected in the measurement sample, Ray of the Fe characteristic X-ray of the Fe target by the Fe target conduit as the characteristic X-ray having an energy lower than the X-ray absorption edge (6.540 keV) of the element Mn, which is lower than the X-ray absorption edge (5.989 keV) 6.403 keV). Accordingly, Cr can be detected with a clear contrast using an inexpensive X-ray tube.

The X-ray permeability test apparatus of the present invention can extract only the Fe-K? Characteristic X-ray (6.403 keV) using a filter of Mn (X-ray absorption edge = 6.540 keV) foil and irradiate the measurement sample.

According to the present invention, the following effects are exhibited.

That is, according to the X-ray penetration inspection apparatus and the X-ray penetration inspection method of the present invention, it is possible to provide an X-ray transmission inspection method which is lower than the X-ray absorption edge of one element included in the measurement sample, Since a contrast image is obtained from the transmitted image obtained by irradiating the X-ray to the sample, a clear contrast image can be obtained for a specific element to be detected. Further, a filter formed of an element having an X-ray absorption edge of the energy between the Kα line and the Kβ line of the characteristic X-ray by the X-ray tube is disposed between the sample and the X- So that the contrast of the detection element to be measured can be obtained more clearly even if there are elements having atomic numbers close to each other.

Therefore, by using the X-ray penetration inspection apparatus and the X-ray penetration inspection method, for example, it is possible to perform foreign matter detection of a specific element in a lithium ion secondary battery or the like with high accuracy and promptly.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a schematic overall configuration diagram showing an embodiment of an X-ray penetration inspection apparatus and an X-ray transmission inspection method according to the present invention.
2 is a diagram showing the relationship between the X-ray energy and the X-ray transmittance in the embodiment of the present invention.
Fig. 3 (a) is an explanatory diagram showing a transmission image of X-rays in the case where a portion having a different thickness locally in the X-ray transmission of the embodiment of the present invention is included. (b) is an explanatory diagram showing the transmission phase of X-rays in the case where foreign matter is contained in the surface layer in X-ray transmission according to the embodiment of the present invention.
Fig. 4 (a) is an explanatory view showing a transmission image of X-rays in the case where a conventional X-ray transmission portion includes portions having different thicknesses locally. (b) is an explanatory diagram showing the transmission phase of X-rays in the case where foreign matter is contained in the surface layer in the conventional X-ray transmission.

Hereinafter, one embodiment of the X-ray penetration inspection apparatus and X-ray transmission inspection method according to the present invention will be described with reference to Figs. 1 to 3. Fig.

As shown in Fig. 1, the X-ray penetration inspection apparatus of the present embodiment has an energy lower than the X-ray absorption edge of one element included in the measurement specimen S and higher than the X-ray absorption edge of the detection element An X-ray detector 13 for receiving a transmitted X-ray when the X-ray is transmitted through the measurement sample S and detecting the intensity of the transmitted X-ray; And a display section 18 for displaying a transmission image showing the distribution of the intensity of the detected transmission X-ray.

The X-ray penetration inspection apparatus further comprises a belt conveyor 16 as a sample stage which is movable in the horizontal direction by placing the measurement specimen S and a control unit 17 connected to each of the above-described structures and controlling each of them have.

Further, in the X-ray penetration inspection apparatus, an element having an X-ray absorption edge of the energy between the Kα line and the Kβ line of the characteristic X-ray from the X-ray conduit is interposed between the measurement specimen S and the X- And the formed filter F1 is disposed.

The measurement specimen S is, for example, an electrode used in a lithium ion secondary battery or the like. The detection element is, for example, Cr in Fe or SUS in which contamination of the electrode is likely to occur.

When the detection element is Fe, the Ni-guiding element having the Ni target is adopted as the X-ray guiding element 11. The Ni-K? Characteristic X-ray (7.477 keV) is emitted from the X-ray tube port 11 of the Ni-port as an X-ray having an energy higher than the K absorption edge of Fe (7.111 keV), for example.

At this time, the filter F1 employs a Co foil.

Further, when the detection element is Cr, the X-ray guiding element 11 employs an Fe guiding element having an Fe target.

An Fe-K alpha characteristic X-ray (6.403 keV) is emitted as an X-ray having an energy higher than the K absorption edge of Cr (5.988 keV), for example, from the X-ray conduit 11 of the Fe conduit.

At this time, Mn foil is adopted as the filter F1.

The energy of the characteristic X-ray which can be employed as X-ray and the energy of the X-ray absorption edge of the element that can be employed as the filter F1 are shown in Table 1 below as an example, when Fe or Cr is used as the detection element.

<Table 1>

In these X-ray conduits, thermal electrons generated from filaments (positive electrodes) in the conduit are accelerated by a voltage applied between a filament (anode) and a target (cathode) And the like.

The X-ray detector 13 is an X-ray line sensor disposed below the belt conveyor 16 so as to oppose the corresponding X-ray tube 11. Examples of the X-ray line sensor include a scintillator system in which X-rays are converted into fluorescence by a fluorescent plate and converted into current signals in a light receiving element arranged in a row, a semiconductor system in which a plurality of semiconductor detection elements are arranged in a row . Further, these X-ray sensors may be X-ray area sensors in which light receiving elements are arranged in two dimensions in addition to a line in a row.

The control unit 17 is a computer configured by a CPU or the like.

The arithmetic unit 15 calculates the transmission image by performing the image processing based on the signal from the X-ray detector 13 inputted through the control unit 17 and displaying the image on the display unit 18 Processing circuits, and the like. The processing circuit of the arithmetic unit 15 may be provided in the control unit 17 to integrate them. Further, the display section 18 can display various information under the control of the control section 17.

Next, an X-ray penetration inspection method using the X-ray penetration inspection apparatus of the present embodiment will be described with reference to Figs. 1 to 3. Fig. In this X-ray penetration inspection method, for example, the measurement sample S is a lithium cobalt oxide electrode, the foreign substance X contained therein is iron, the detection element is Fe, and the X- Ni conduit is adopted.

First, the measurement specimen S is moved to a position opposite to the X-ray guide opening 11 by the belt conveyor 16.

The Ni-Kα characteristic X-ray is irradiated as X-ray from the X-ray tube 11 of the Ni port to the measurement sample S and the X-ray transmitted through the measurement sample S by the X- Line. At this time, the entire sample is scanned by moving the measurement specimen S to the belt conveyor 16, and the entire intensity distribution is acquired for the transmitted X-rays.

At this time, the X-ray (Ni-K? Characteristic X-ray = 7.477 keV) emitted from the X-ray tube port 11 of the Ni conduit passes through the X of Co, which is one of the constituent elements of the lithium cobaltate battery Ray absorption edge (7.709 keV) and is higher than the X-ray absorption edge (7.112 keV) of the detection element (Fe). Therefore, lithium cobalt oxide itself which is the measurement sample (S) permeates and is absorbed by iron (X), whereby a high contrast image is obtained. Before irradiation with the measurement specimen S, a characteristic X-ray (Ni-K beta characteristic X-ray (8.264 keV) or the like) higher in energy than the X-ray absorption edge of Co or background X- ), And only the Ni-K? Characteristic X-ray (7.477 keV) is irradiated onto the measurement sample S.

Here, &quot; one element contained in the measurement sample &quot; is defined as &quot; one element contained in the measurement sample, which is lower than the X-ray absorption edge of one element included in the measurement sample, Quot; to the measurement sample &quot; is selected. Therefore, the case of this embodiment is one of the constituent elements of the lithium cobalt oxide battery, and it is Co in the relationship of the detecting element and the X-ray.

The arithmetic unit 15 performs image processing on the intensity distribution of the transmitted X-rays thus obtained to produce a transmission image.

In addition, the X-ray transmittance of the lithium cobalt oxide electrode is, as shown in Fig. 2, when an impurity of Fe of 20 mu m is contained, as compared with the case where there is no foreign matter, The X-ray transmittance is lowered. The X-ray characteristic Ni-K? Characteristic X-ray has energy corresponding to the high energy of the X-ray absorption edge of Fe.

Therefore, as shown in Fig. 3 (a), a thick part (for example, an electrode material in which the lithium cobalt oxide film 2 is laminated on both surfaces of the Al film 1) of the measurement sample S 2a, there is no clear contrast in the portion corresponding to the locally thick portion 1a in the transmitted image T1 by the X-ray tube 11 of the Ni conduit. 3 (b), when the foreign object X of Fe is present in the measurement sample S, the foreign matter X (X) is formed on the transmission image T1 by the X- ), A clear contrast appears in the portion corresponding to the pixel. That is, since the X-ray transmittance of the Ni-K? Characteristic X-rays having an energy higher than the X-ray absorption edge of Fe is lower than that of the foreign substance X of Fe, the portion of the foreign matter X, (Dark portion), resulting in contrast.

In the above description, the X-ray transmission inspection method for detecting foreign matter (X) in the lithium cobalt oxide electrode is exemplified. However, the present invention is applicable to an electrode material used for a lithium ion secondary battery, The present invention is equally applicable to the inspection of foreign matter in the lithium oxide or the inspection of foreign matters in the laminated material of Al (aluminum) and C (graphite) used for the cathode plate.

With respect to the X-ray transmittance of these materials, when there is a foreign matter (X) of Fe, the X-ray transmittance decreases at all in the X-ray absorption edge of Fe. Therefore, even in the case of detecting the foreign substance X in these materials, even when the foreign matter X in these materials is detected, the energy of the X-ray absorption edge of the main element constituting the material is lower than the energy of the X- (For example, Ni-K? Characteristic X-rays from the Ni conduit), a contrast image in which a portion of the foreign matter X is emphasized can be obtained.

As described above, in the X-ray penetration inspection apparatus and the X-ray inspection method of the present embodiment, X-rays having an energy lower than the X-ray absorption edge of one element included in the measurement sample and higher than the X- Since a contrast image is obtained from the transmitted image T1 obtained by irradiating the measurement specimen S, a clear contrast image can be obtained for a specific detection element. That is, not the X-rays in which various kinds of energy such as white X-rays are mixed but the characteristic X-rays having the X-ray absorption edge on the high energy side of the X-ray absorption edge of the detection element, , It is possible to obtain a clear contrast image of the element to be measured even in the presence of other elements approaching the atomic number by irradiating characteristic X-rays that cause a difference in the transmission X-ray detection amount.

A filter F1 formed of an element having an X-ray absorption edge of the energy between the Kα line and the Kβ line of the characteristic X-ray from the X-ray tube is arranged between the measurement sample S and the X- It is possible to cut unwanted radiation (not only the characteristic X-rays from the X-ray tube 11 but also characteristic X-rays or background X-rays having higher energy than these) by the filter F1. Therefore, only the desired characteristic X-rays are extracted and irradiated onto the measurement specimen S, so that the contrast of the element to be measured becomes clearer.

When the sample to be measured includes lithium cobalt oxide, the X-ray tube 11 of the Ni-base capable of emitting the characteristic X-ray of Ni located at high energy of the X-ray absorption edge of Fe when Fe is used as the detection element, It is possible to detect foreign matter X of Fe in a clear contrast image by using an inexpensive X-ray tube.

Further, since the filter is a Co foil, only the Ni-K? Characteristic X-ray (7.477 keV) can be extracted by the X-ray absorption edge of Co (7.709 keV). That is, the Ni-K beta characteristic X-ray (8.264 keV) is cut by the X-ray absorption edge of Co (7.709 keV).

In the case where the measurement sample contains lithium manganese oxide, the X-ray tube 11 of the Fe-guidewire capable of emitting the characteristic X-ray of Fe located at the high energy of the X-ray absorption edge of Cr when Cr is used as the detection element, The foreign matter X such as SUS containing Cr can be detected with a clear contrast by using an inexpensive X-ray tube.

Since the filter F1 is a Mn foil when the X-ray conduit 11 is an Fe conduit, only the Fe-K? Characteristic X-ray (6.403 keV) can be extracted by the X-ray absorption edge of Mn (6.537 keV) . That is, the Fe-K beta characteristic X-ray (7.057 keV) is cut by the X-ray absorption edge of Mn (6.537 keV).

Further, the technical scope of the present invention is not limited to the above-described embodiment, but various modifications can be made within the scope of the present invention.

11: X-ray tube 13: X-ray detector
15: calculating section 16: belt conveyor
17: control unit 18:
F1: filter S: measurement sample
T1: transmitted phase X: detection target (foreign object)

Claims (8)

An X-ray tube for irradiating the sample with a characteristic X-ray having energy lower than the X-ray absorption edge of one element included in the electrode material for the lithium ion secondary battery and higher than the X- (Tube)
An X-ray detector that receives the transmitted X-rays when the characteristic X-rays penetrate the measurement specimen and detects the intensity thereof,
An operation unit for obtaining a contrast image from a transmission image showing a distribution of the intensity of the transmitted X-ray,
And an element which is an X-ray absorption edge of energy between the K alpha line and the K beta line of the characteristic X-ray between the measurement sample and the X-ray conduit,
Wherein the measurement sample contains lithium cobaltate,
Wherein the X-ray guiding element is an Ni target guiding element,
Wherein the detection element is Fe. The apparatus according to claim 1, wherein the filter is a Co foil. An X-ray tube for irradiating the sample with a characteristic X-ray having energy lower than the X-ray absorption edge of one element included in the electrode material for the lithium ion secondary battery and higher than the X- (Tube)
An X-ray detector that receives the transmitted X-rays when the characteristic X-rays penetrate the measurement specimen and detects the intensity thereof,
An operation unit for obtaining a contrast image from a transmission image showing a distribution of the intensity of the transmitted X-ray,
And an element which is an X-ray absorption edge of energy between the K alpha line and the K beta line of the characteristic X-ray between the measurement sample and the X-ray conduit,
Wherein the measurement sample contains lithium manganese oxide,
Wherein the X-ray guiding element is an Fe target guiding element,
Wherein the detection element is Cr. The X-ray penetration inspection apparatus according to claim 3, wherein the filter is Mn foil. As a measurement sample, a characteristic X-ray irradiation which is lower than the X-ray absorption edge of one element contained in the electrode material for a lithium ion secondary battery and which irradiates the sample with a characteristic X-ray having energy higher than that of the X- Step,
A transmitted X-ray detecting step of receiving transmitted X-rays when the X-rays are transmitted through the measurement specimen and detecting the intensity of the transmitted X-
And a calculation step of obtaining a contrast image obtained by creating a transmission image showing a distribution of the intensity of the transmitted X-rays, the method comprising the steps of:
Wherein the step of irradiating the characteristic X-rays comprises the steps of disposing a filter including an element which is an X-ray absorption element with a higher energy than the characteristic X-ray between the measurement sample and the X-ray conduit, , &Lt; / RTI &gt;
Wherein the measurement sample contains lithium cobaltate,
Wherein the X-ray guiding element is an Ni target guiding element,
Wherein the detection element is Fe. The inspection method according to claim 5, wherein the filter is Co foil. As a measurement sample, a characteristic X-ray irradiation which is lower than the X-ray absorption edge of one element included in the electrode material for a lithium ion secondary battery and irradiates the characteristic X-ray having energy higher than that of the X- Step,
A transmitted X-ray detecting step of receiving transmitted X-rays when the X-rays are transmitted through the measurement specimen and detecting the intensity of the transmitted X-
And a calculation step of obtaining a contrast image obtained by creating a transmission image showing a distribution of the intensity of the transmitted X-rays, the method comprising the steps of:
Wherein the step of irradiating the characteristic X-rays comprises the steps of disposing a filter including an element which is an X-ray absorption element with a higher energy than the characteristic X-ray between the measurement sample and the X-ray conduit, , &Lt; / RTI &gt;
Wherein the measurement sample contains lithium manganese oxide,
Wherein the X-ray guiding element is an Fe target guiding element,
Wherein the detection element is Cr. The inspection method according to claim 7, wherein the filter is Mn foil.

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